SecretsManager: Add (en/de)cryption packages (#104923)

Merging the code as-is from the feature branch: secret-service/feature-branch

Co-authored-by: PoorlyDefinedBehaviour <brunotj2015@hotmail.com>
Co-authored-by: Dana Axinte <53751979+dana-axinte@users.noreply.github.com>
Co-authored-by: Leandro Deveikis <leandro.deveikis@gmail.com>
Co-authored-by: Mariell Hoversholm <mariell.hoversholm@grafana.com>
Co-authored-by: Michael Mandrus <michael.mandrus@grafana.com>

pkg/registry/apis/secret/encryption/cipher/cipher.go

@@ -0,0 +1,28 @@
+package cipher
+
+import (
+	"context"
+)
+
+const (
+	AesCfb = "aes-cfb"
+	AesGcm = "aes-gcm"
+)
+
+type Cipher interface {
+	Encrypter
+	Decrypter
+}
+
+type Encrypter interface {
+	Encrypt(ctx context.Context, payload []byte, secret string) ([]byte, error)
+}
+
+type Decrypter interface {
+	Decrypt(ctx context.Context, payload []byte, secret string) ([]byte, error)
+}
+
+type Provider interface {
+	ProvideCiphers() map[string]Encrypter
+	ProvideDeciphers() map[string]Decrypter
+}